HYBRID INTERNET TRAFFIC CLASSIFICATION TECHNIQUE1

Accurate and real-time classification of network traffic is significant to network operation and management such as QoS differentiation, traffic shaping and security surveillance. However, with many newly emerged P2P applications using dynamic port numbers, masquerading techniques, and payload encryption to avoid detection, traditional classification approaches turn to be ineffective. In this paper, we present a layered hybrid system to classify current Internet traffic, motivated by variety of network activities and their requirements of traffic classification. The proposed method could achieve fast and accurate traffic classification with low overheads and robustness to accommodate both known and unknown/encrypted applications. Furthermore, it is feasible to be used in the context of real-time traffic classification. Our experimental results show the distinct advantages of the proposed classification system, compared with the one-step Machine Learning (ML) approach.     

新媒体互动平台设计与实现

本文以北京电视台新媒体现场互动系统为案例,详细介绍了电视台报名、投票、抽奖为基础的互动方案设计思路和技术方案,并结合当下热门的Wi-Fi等技术,为互联网化下的电视台互动系统建设提供了一种新型的建设思路.     

频率覆盖3.2～6.1 GHz的CMOS LC VCO

通过提高MIM电容的调整范围,实现了一个覆盖3.2～6.1 GHz的CMOS LC VCO.该VCO使用0.18μm射频CMOS工艺制作,芯片面积约为1260μm×670μm.当输出5.5GHz时,VCO内核消耗功率为17.5mW;在100kHz频偏处的相位噪声是～101.67dBc/Hz.     

A First Principles Study of Ferroelectricity and Magnetism Coexisting in Fe-Doped K<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>NbO<Subscript>3</Subscript>

First-principles calculations were performed to investigate the coexistence of ferroelectricity and magnetism in Fe-doped tetragonal K_0.5Na_0.5NbO₃ (KNN) with different Fe concentrations. It was found that all three systems can possess both magnetism and ferroelectricity, and the magnetism becomes stronger with an increase in the concentration of Fe. The magnetic properties are due to ferromagnetism of Fe, and the Fe-Nb and Fe-O bonds induce magnetic moments on Nb and O atoms. Ferroelectricity comes from the hybridization of Nb and O, as in the case of pure KNN. The predicted results provide insight into the origin of the induced magnetic moments and an approach for obtaining multiferroic materials.     

带末端攻击角度约束的三维最优导引律研究

针对导弹对目标实施大角度攻击的作战需求,运用飞行力学和最优控制理论,设计了带终端攻击角度约束的三维空间最优导引律.在设计过程中,将三维空间分成纵向和航向两个导引平面,分别设计两个平面的最优导引律,并在纵向平面上考虑攻击角度约束,使得导弹在命中点的弹道倾角满足约束条件.最后分别针对静止目标和慢速运动目标进行了仿真研究.     

某雷达目标模拟器的软硬件设计

介绍某相控阵雷达目标模拟器的设计,该目标模拟器以PCI04为硬件核心,通过软件设计实现各项功能,快速有效地完成了雷达的静态、动态实验室调试。     

Balancing MXene Surface Termination and Interlayer Spacing Enables Superior Microwave Absorption

Surface chemistry and interlayer engineering determines the electrical properties of 2D MXene. However, it remains challenging to regulate the surface and interfacial chemistry of MXene simultaneously. Herein, simultaneous modulation of Ti₃C₂T_x MXene surface termination and layer spacing by alkali treatment are achieved. The electrical and electromagnetic properties of Ti₃C₂T_x are investigated in detail with respect to KOH and ammonia concentration dependence. A high concentration of KOH caused the Ti₃C₂T_x layer spacing to expand to 13.7 Å and the surface O/F ratio to increase to 33.84. Because of its weaker ionization effect, ammonia provides finer tuning compared to the drastic intercalation of KOH with a thorough sweeping of the F-containing groups. Ti₃C₂T_x is enriched with conductive -OH termination after ammonia treatment, which achieves an effective balance with the increased interlayer resistance. Therefore, NH₃H₂O-Ti₃C₂T_x achieves broad-band impedance matching and exhibits an efficient microwave loss of −49.1 dB at a low thickness of 1.7 mm, with an effective frequency bandwidth of 3.9 GHz. The results herein optimize the electrical properties of Ti₃C₂T_x using surface and interfacial chemistry to achieve broad microwave absorption, providing a framework for enhancing the electromagnetic wave loss of intrinsic MXene.     

Local Electronic Structure Modulation Enables Fast-Charging Capability for Li-Rich Mn-Based Oxides Cathodes With Reversible Anionic Redox Activity

Anionic and cationic redox chemistries boost ultrahigh specific capacities of Li-rich Mn-based oxides cathodes (LRMO). However, irreversible oxygen evolution and sluggish kinetics result in continuous capacity decay and poor rate performance, restricting the commercial fast-charging cathodes application for lithium ion batteries. Herein, the local electronic structure of LRMO is appropriately modulated to alleviate oxygen release, enhance anionic redox reversibility, and facilitate Li⁺ diffusion via facile surface defect engineering. Concretely, oxygen vacancies integrated on the surface of LRMO reduce the density of states of O 2p band and trigger much delocalized electrons to distribute around the transition metal, resulting in less oxygen release, enhancing reversible anionic redox and the MnO₆ octahedral distortion. Besides, partially reduced Mn and lattice vacancies synchronously stimulate the electrochemical activity and boost the electronic conductivity, Li⁺ diffusion rate, and fast charge transfer. Therefore, the modified LRMO exhibits enhanced cyclic stability and fast-charging capability: a high discharging capacity of 212.6 mAh·g⁻¹ with 86.98% capacity retention after 100 cycles at 1 C is obtained and to charge to its 80%, SOC is shortened to 9.4 min at 5 C charging rate. This work will draw attention to boosting the fast-charging capability of LRMO via the local electronic structure modulation.     

Research on the identification performance of UHF RFID system considering the correlation of cascaded channel

The identification rate of UHF RFID system was restricted by multipath propagation effects.The system identification performance was studied considering the correlation coefficient between forward and reverse channels.Based on the generalized Rician fading channel model,the analytical expression of identification rate was derived under independent,full correlation and correlation cases.Compared with the existing analysis,the proposed uniform calculation formula of identification rate was for any correlation coefficient and kinds of channel conditions.The numerical computation and Monte-carlo simulations show that the influences of different correlation coefficients,channel conditions,sensitivity and distance on the identification rate.     

PLC的大型牵伸卷绕机的应用研究

本文介绍了大型牵伸卷绕机的计算机控制系统，以西门子MMV型变频器为驱动装置，西门子PLC300为控制核心，根据西门子USS协议和MPI协议，实现PLC与变频器、TP27触摸显示屏的通信，取得了较高的控制精度和稳定性，充分满足生产过程的需要，具有广阔的应用前景。